Graphene oxide with tailored low thermal conductivity by defect engineering, for thermal insulation

The present study suggests a viable strategy for the development of next-generation nanomodified material systems, establishing defect engineering for tailoring the intrinsic low thermal conductivity of graphene oxide. Starting from a modified Hummers-based synthesis route for GO, two complementary defect engineering strategies were investigated for suppressing thermal transport, namely lateral size control by mechanical treatment methods such as ultrasonication and surface defect introduction by oxygen plasma treatment. The Raman I D /I G defect index was found to increase with both sonication duration and oxygen plasma exposure, confirming the progressive introduction of structural defects through each mechanism. Hybrid treatments yielded synergistic enhancements in the defect index, with values reaching 20% higher than the as-synthesized nanocarbon. Thermal conductivity exhibited plausible reductions in value of ca. 26%, comparable with the value measured for an independent graphene oxide variant, stemming from oxidation of pristine graphene nanoplatelets. The finding demonstrates that chemical oxidation is equally effective to mechanical treatment for thermal transport suppression. While the two defect engineering pathways operate through distinct and complementary mechanisms, namely edge-related phonon scattering for mechanical treatment and basal-plane sp³ defect introduction for chemical treatment, their synergistic combination is envisioned to achieve further reductions in thermal conductivity.